Fix Django 2.x incompatibility in pandocfield
Fix Django 2.x incompatibility in pandocfield

Honestly, seeing the error message "render() got an unexpected keyword
argument 'renderer'" almost gave me a heart attack. Thankfully, fixing the
pandocfield widget was easy enough. Note to self: never implement custom
Django fields in the future!

JaapJoris/bps,JaapJoris/bps